KR20170075669A - Injection moulding method for the production of moulded parts, moulded part produced by means of injection moulding and also injection mould - Google Patents

Abstract

The present invention relates to a method of making an injection molded reinforced molded part in which the fiber orientation is specifically localized. Preferably, the additional heating, which is dynamically controlled in the injection mold wall, is used (channel heatable to a temperature) and the local cavity region is heated to the solidification temperature of the polymer (plastic molding compound) , Higher than the crystallization temperature for partially crystalline plastic materials or higher than the glass transition temperature for amorphous plastic materials).

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding method for manufacturing a molded part, a molded part manufactured by injection molding and an injection mold,

The present invention relates to a method of making an injection molded reinforced molded part in which the fiber orientation is specifically localized. Preferably, the additional heating, which is dynamically controlled in the injection mold wall, is used (channel heatable to a temperature) and the local cavity region is heated to the solidification temperature of the polymer (plastic molding compound) , Higher than the crystallization temperature for partially crystalline plastic materials or higher than the glass transition temperature for amorphous plastic materials).

In conventional injection molding, the mold wall temperature is generally controlled to a temperature equal to or lower than the solidification temperature (the crystallization temperature for the partially crystalline plastic material or the glass transition temperature for the amorphous plastic material) for each plastic material, . Whereby the central portion of the melt front remains fluid and the plastic material is directed forward in the cavity by the injection pressure and the edge zone near the mold wall rapidly cools and solidifies. When the mold cavity is filled and the plastic material is completely solidified, the molded part is released from the mold. In the entire injection molding cycle, the mold walls are maintained at the same temperature. Thus, mold temperature control can be understood as cooling to dissipate the thermal energy of the melt, including any possible crystallization heat introduced into the mold during each injection.

In the case of a thin wall at the same time as a long flow path, this can lead to freezing of the cross section, thus preventing complete filling of the cavity. Also, it can not be completely reproduced on structured surfaces and high-gloss surfaces. Further, when the flow wires are flowed together, a visible bonding line is formed.

The so-called thermoforming mold temperature control provides a solution to the above-mentioned problem. Through further heating, the cavity is heated upon injection to a level of melting temperature (at least above the crystallization temperature) of the partially crystalline plastic material (or glass transition temperature in the case of amorphous plastic material), and after completion of the mold filling, Is cooled to a temperature significantly lower than the temperature. The heating of the mold walls is essentially uniform over the whole surface. As a result of the higher melting temperatures and mold temperatures that can be achieved in this manner during injection molding, the viscosity of the polymer melt is significantly reduced and the molding of the problematic part is improved or both become possible. Temperature changes should be achieved as quickly as possible to ensure adequate productivity.

Advantages of thermoforming mold temperature control:

* Minimize component distortion and distortion

* Highly polished surface even through foam plastic material

Avoid traces of fiber on the surface of molded parts

* Molding of components with thin walls is possible

* Reduced cycle time for thick wall components

* High homogeneity and robustness

* Seam line not visible

In this type of mold temperature control, the entire cavity (mold wall) is heated or cooled during the injection molding cycle. In the case of the unreinforced molding compound, a definite improvement in the bonding line strength can be confirmed. In contrast, when a reinforced molding compound, such as carbon fiber or glass fiber, is injected, the fiber orientation is defined by the gate position and the flow path created therefrom, The fiber orientation is not changed by the strain temperature control. Thus, some actual joining lines disappear visually from the surface of the molded part, but do not disappear from the molded part itself. The bond line strength is never improved because the strength of the molded part based on the reinforced molding compound is dependent on the fiber orientation.

It is therefore an object of the present invention to provide a new injection molding method capable of adjusting the orientation of the reinforcing fibers in the plastic material melt in a manner defined by locally limited temperature mold temperature control, Stress direction) is improved.

It is also an object of the present invention to a corresponding molded part in which a specific alignment of the fiber orientation is present. It is a further object of the present invention to provide a corresponding injection mold for the production of molded parts according to the invention or for the implementation of the method according to the invention.

This object is achieved in connection with the method according to the invention of claim 1, the correspondingly produced molded part according to claim 17, the injection mold according to claim 19. Each dependent term represents a preferred improvement.

The present invention relates to an injection molding method for producing a molded part made of a thermoplastic molding compound, wherein the molding compound comprises reinforcing fibers.

The thermoplastic molding compound is filled in an injection mold in the plasticized state, and the injection mold has a cavity for reproducing the appearance of the molded part to be produced. Thereby, the thermoplastic molding compound is heated to the prescribed temperature &thetas; _FM , whereby the temperature is chosen very high so that the thermoplastic molding compound is in a plasticized state in which injection molding can be carried out.

Whereby the injection mold has a gate position at which the thermoplastic molding compound can be fed into the injection mold cavity. Generally, the injection mold has a single gate position, but the present invention is not limited to any particular embodiment, and it is also possible that the injection mold has a plurality of gate positions.

According to the method according to the present invention, an injection mold cavity is provided in which the injection mold cavity is filled, fully filled, or partially filled up to the filling amount specified by the thermoplastic molding compound. And filling means that a larger volume of the thermoplastic molding compound is fed into the cavity of the injection mold as compared to the volume of the injection mold cavity. Thus, overfilling of the injection mold cavity means that a proportion of the thermoplastic molding compound, i.e., the molding compound in excess of the volume, must exit the injection mold cavity. This can be done, for example, through the discharge openings provided for this purpose in the injection mold cavity, as well as by forming an injection mold and allowing the cavity to be filled with an excess amount of molding compound exiting the contact point through two sealed partial molds . ≪ / RTI > Likewise, it is possible that the injection mold cavity is completely filled, and the volume of the thermoplastic molding compound corresponding to the volume of the injection mold cavity is correctly supplied into the injection mold cavity. In addition, it is further possible for the injection mold cavity to be filled only partially, e.g. at a prescribed filling level, and a smaller volume of the thermoplastic molding compound is supplied into the injection mold compared to the volume of the injection mold cavity.

According to the present invention, the injection mold cavity in one or more walls has a channel that can be heated to one or more of the transition temperatures along the trajectory. Uneven heating of the walls defining the injection mold cavity is possible by channels that can be heated to one or more of the transition temperatures. By means of a channel which can be heated by one or more temperature changes, a temperature gradient can be realized in the injection mold wall. In comparison with the known technology, the temperature control technique is only limited to locally limited temperature control, which does not allow full-surface heating of the injection mold cavity wall but allows only the above-described implementation.

Thus, channels or channels that can be heated by the temperature change are embedded in the wall of the injection mold. Thus, the channels that can be heated by the temperature change are operated for temperature control of the surface of the injection mold wall and the cavity. It is understood that the locus of channels or channels that can be heated by the temperature of the transition is a direction in which the channels or channels are parallel to the wall defining the injection mold cavity. Preferably, the trajectory is a vector component extending parallel to the wall defining the injection mold cavity, reproducing the path of channels or channels that can be heated to a temperature at the protrusions at the surface. When a channel that can be heated by the temperature change is uniformly formed into a wide strip, a locus is formed along the center line of the channel. The determination of the locus along the centerline can likewise be performed in the case of a variable width of the channel which can be heated by the temperature change.

The trajectory is preferably differentiable and / or constant over the entire path; Is excluded in the region where branching of the channel and its corresponding corresponding trajectory are provided. The path of the trajectory given as an example may be linear, curved, wavy or circular for common inflow and outflow.

According to a preferred embodiment, it is provided that there is a channel which can be heated by only one single temperature, in the wall of the injection mold, or a channel which can be heated by one single temperature change per wall of the injection mold. Likewise, channels that can be heated to one or more of the transition temperatures can extend in a plurality of regions that have branch points and can be re-tied together to form channels that are heatable at a single temperature.

If the injection mold has channels that can be heated to a plurality of temperatures, uniform heating of the mold cavity walls is not to be ensured and they must be ensured to be in a sufficiently large space so that a non-uniform temperature profile is achieved. Therefore, in the injection molding process, it is ensured that the thermoplastic molding compound is still in a processable state, i.e., a molten state, in a region of the temperature-sensitive channel or temperature-change channels where a higher viscosity is provided in the remaining region or the thermoplastic molding compound is solidified. .

For the process according to the invention, since the previous filling of the injection mold, filled during and / or filled, it is permanently or at least temporarily to the area of the injection mold having at least one byeonon channel of the wall is set to a temperature θ _VT injection mold and the rest of the wall of the set temperature θ _{W, W} is θ <θ _VT. This temperature difference is maintained at least until the final cooling of the thermoplastic molding compound.

The temperature difference in the different regions of the injection mold described above can be maintained during the entire duration of the injection molding cycle, i. E. During the method according to the invention, but at least during the cooling of the thermoplastic molding compound until the thermoplastic molding compound is solidified Lt; / RTI &gt; This cooling can be achieved, for example, by no further heating or by actively cooling the entire injection mold.

Similarly, at the beginning of the injection molding process, it is preferentially θ _W = θ _VT , that is, the entire injection mold can have the same temperature. In merely process steps, i.e., for example during filling or overfilling, or both during filling and overfilling, channels which can be heated by the temperature can be temperature controlled to a higher temperature than the rest of the area of the injection mold. This allows the temperature difference to be achieved, for example, by lowering the wall of the injection mold in the remaining area without further heating or cooling, for example the temperature in the temperature-change channel is maintained by heating.

Temperature control of the channels or channels that can be heated by the transforming temperature is enabled by selective heating of the temperature-changing channels.

The heating of the channel which can be heated by the temperature of the transition can be achieved by a heating method known in the art. Such possibilities are known in the art and are described, for example, in MH Deckert, Technical University Chemnitz, published on September 16, 2011, entitled " Beitrag zur Entwicklung eines hochdynamischen variothermen Temperiersystems fur Spritzgie Bwerkzeuge " A paper on control system development). In addition, all possibilities set forth herein for realizing the temperature-controlled temperature control system can be used for temperature control of channels which can be heated to the temperature of the present invention.

After overfilling, full filling or partial filling at the specified filling level, the thermoplastic molding compound comprising the reinforcing fibers is cooled until solidified, and the molded part thus produced is then released from the injection mold.

Thus, an essential aspect of the present invention is the presence of channels that can be heated to one or more of the transition temperatures extending from the wall of the injection mold along the defined trajectory. By these or by their extended temperature channels or channels, specific temperature control of the plastic molding compound located in the injection mold cavity is adjustable along this trajectory. Thus, the temperature distribution at the wall surface of the injection mold cavity is non-uniform and at least temporarily higher temperatures than the rest of the area of the injection mold wall can be achieved along the locus of channels or channels that can be heated by the temperature. Thus, thermoplastic molding compounds that are filled into the injection mold cavity can be additionally heated in these regions independently of the remaining regions, resulting in higher temperature levels and thus the molding compound temperature in these regions exceeds the level of the remaining molding compound Which can lead to higher temperature levels. As a result, the viscosity of the thermoplastic molding compound can be reduced due to additional heating and higher temperature levels achieved, and the flow of the thermoplastic molding compound along with the trajectory of channels or channels that can be heated by the temperature can be assisted. Thus, the flow of the thermoplastic molding compound along this locus is assisted during filling of the injection mold cavity, during overfilling, during full filling or during partial filling. By the supplemental flow of the thermoplastic molding compound along the locus, the orientation of the reinforcing fibers, which are likewise dispersed in the thermoplastic molding compound, is carried out along the locus of the channels which can be heated by the thermo-transformation. So that a specific orientation of the reinforcing fibers can be carried out according to the trajectory of channels or channels that can be heated to a temperature that extends along the trajectory.

A preferred embodiment of the method according to the invention is provided with an injection mold having at least one overflow opening. When filling the injection mold, an excess amount of thermoplastic molding compound emerges from the injection mold cavity through the overflow opening. Preferably, an overflow cavity is connected to the overflow opening, wherein the overflow cavity is in fluid communication with the overflow opening and in fluid communication with the injection mold cavity through the overflow opening. Thus, the overflow cavity serves to recover an excess amount of thermoplastic molding compound exiting the overflow opening during overfilling of the injection mold. The recovered thermoplastic molding compound can be recycled and reused during the process according to the invention. A channel that is heatable by one or more of the temperatures may be induced to the at least one overflow opening beginning at the gate position of the injection mold so that the thermoplastic molding compound can escape from the injection mold cavity when the injection mold is overfilled, Lt; RTI ID = 0.0 &gt; overflow &lt; / RTI &gt; cavities.

With respect to the injection molding method according to the present invention in which the injection mold is filled, a filling step (a) of the injection mold, which can be designed as an atmospheric step while no additional molding compound is supplied to the injection mold, The following temperature control is preferred for step (b) between c) and filling and charging.

(1) Constant temperature control: Temperature θ _W And θ _VT is not changed during step (a) to (c), the relation θ _W <θ _VT Is always applied. θ _W is the low temperature level, and θ _VT is the high temperature level.

(2) Heating of the conduction channel: [theta] _W is constant at low temperature levels during steps (a) - (c). In step (a),? _W And θ _VT is preferably a different, in particular θ _W θ _{= VT} to less than 50K. θ _VT becomes the high temperature level in step (b) and θ _W for steps (b) and (c) lt; _VT .

(3) Cooling of the remaining molding walls: This alternative is characterized in that [theta] _VT is kept constant at the high temperature level during steps (a) - (c) and that [theta] _w in step (a) has a high temperature level. In step (a),? _W And θ _VT preferably has a similar temperature as the difference is less than 50K, and particularly, θ _W θ _{= VT.} The temperature? _W is lowered to the low temperature level in step (b), and? _W &lt;? _VT for steps (b) and (c).

In step (c), the temperature? _W And θ _VT of the relationship is the same as temperature control (1) to (3) mentioned above, always θ _W <? _VT ,? _VT is always at a high temperature level, and? _W is always at a low temperature level. The high temperature level means that the molding compound remains fluid at this temperature range even if it remains in this state for a very long period of time. The low temperature level means that the molding compound is poorly flowable or non-flowable in this temperature range, i. E. In a high viscosity or solid state.

After termination of step (c), the temperature &lt; RTI ID = 0.0 &gt;# _VT &lt; / RTI &gt; is lowered so that the molded part can be released from the mold.

Constant temperature control (1) which makes heating of the temperature-changing channels or cooling of the remaining molding walls unnecessary within steps (a) - (c) is particularly preferred as a result of step (b) being omitted or kept very short.

According to a preferred embodiment in which overfilling of the injection mold is carried out, it is preferred to adopt one or more of the following measures:

- 5 to 100% by volume, preferably 10 to 70% by volume and particularly preferably 15 to 50% by volume of the injection mold cavity volume is overfilled; The volume of the overflow cavity preferably corresponds to the volume ratio of the overfilled cavity. For example, if the volume of the 100% by volume injection mold cavity is overfilled, this means that the volume of the cavity during the injection mold cycle is injected twice into the tool including the overflow cavity.

After a full charge, a waiting time of 2 to 60 seconds is maintained before overfilling and during the waiting time the temperature &lt; RTI ID = 0.0 &gt; _{VT &lt; /} RTI &gt; in the region of the injection mold with one or more temperature- The temperature &lt; RTI ID = 0.0 &gt; _W &lt; / RTI &gt; in the remaining region on the wall of the injection mold Lowered / lowered,

- The filling is continued for a time range of 2 to 60 seconds.

For example, while the remaining area of the injection mold is not heated, adjustment of the temperature difference can be performed by heating only the temperature-change channel of the injection mold.

During the above-mentioned waiting time, no additional feeding of the thermoplastic molding compound into the cavity takes place, which is carried out only after the end of the waiting time. Thus, this additional supply may be the same as the dwell pressure phase in conventional injection molding cycles. During the stand-by time, temperature control is preferably maintained in the region of channels that can be heated by the temperature or channels that can be heated by the temperature. Optionally, cooling may be performed in the remaining region of the cavity wall. Thus, the thermoplastic molding compound in the injection mold cavity can be flown and thermoplasticly processed, while the thermoplastic molding compound in the remaining region of the injection mold cavity can optionally be already cooled and solidified very or completely. During the residence pressure, the flow of the thermoplastic molding compound, if not exclusively, is preferably carried out in the region of the trajectory of the channels or channels which can be heated by the temperature, and as a result of this, A specific orientation of the reinforcing fibers is carried out.

A particular advantage of the process according to the invention is that the orientation of the reinforcing fibers in the thermoplastic molding compound is adjusted due to the temperature difference between the region of the channels which can be heated by one or more temperatures and the remaining region of the injection mold, Lt; RTI ID = 0.0 &gt; anisotropic &lt; / RTI &gt;

In particular, the orientation of the reinforcing fibers is defined by the following orientation tensor (a _ij ) of the group of n reinforcing fibers contained in one finite volume element,

The element a _ij is defined as follows,

The orientation of the fibers is determined by the diagonal elements a ₁₁ , a ₂₂ and a ₃₃ of the orientation tensor (a _ij )

또는

는 각각 k번째 섬유에 평행하게 연장되는 길이 1의 벡터

성분을 나타내며,

or

Lt; RTI ID = 0.0 &gt; A vector of length 1 extending in parallel

Lt; / RTI &gt;

는 로컬 좌표계에서 하나 이상의 변온으로 가열 가능한 채널 영역에서 각각의 고려되는 유한 체적 요소를 나타내며,vector

Represents each considered finite volume element in the channel region that is heatable to one or more of the temperature changes in the local coordinate system,

The x-axis is fixed in each tangential direction to the trajectory of the channel which can be heated to one or more of the thermo-energies in each considered finite volume element,

The y-axis is oriented perpendicular to x,

The z-axis is oriented perpendicular to x and y,

The value of the element a ₁₁ of the orientation tensor (a _ij ) in each given finite volume element is 0.5 or more, preferably 0.5 to 0.98, more preferably 0.6 to 0.95, more preferably 0.65 to 0.9, especially 0.7 to 0.85 , An essentially anisotropic orientation is produced.

Thus, the anisotropic orientation of the fibers can be determined by a representative group of n reinforcing fibers determined for their orientation. Thus, each vector is set for that fiber, so that each vector extends parallel to the fiber considered respectively. Thus, a finite volume element can be selected as a cube having an edge length defined by a dimension smaller than the extension of the region of the channel that can be heated by the temperature change. In general, for example, the resolution determined by spectroscopy can be used to measure finite volume elements. Fibers disposed entirely within the considered finite volume element are not only included in the n number of reinforcing fibers, but are only partially within the finite volume element, being cut by the finite surface of each finite volume element. This finite volume element can be, for example, a voxel whose edge length is in the range of 10 mu m.

For anisotropic orientations, only the orientation for each x-component of the local coordinate system is relevant. For this reason, the above definition of the y-component or z-component of each coordinate system need not necessarily be provided. For the sake of clarity, for example, each y-component of the coordinate system may be considered orthogonal to the walls of the injection mold cavity.

The anisotropy is formed over the entire area of the heatable channel or the variable heatable channels, i.e., at any position of the channel region heatable by the temperature change.

The region in which a heatable channel into a plurality of heatable channels is branched or a channel that can be heated by a plurality of temperature changes for formation of a channel that can be heated by a single temperature is combined is excluded from the above definition. It is to be understood that in these positions or in these regions, preferential orientation of the reinforcing fibers can not be established due to the different orientations caused by the channels which can be heated by a plurality of temperature changes.

The area of the channels that can be heated by the temperature or the temperature that can be heated by the temperature within the finished molded part corresponds to the area enclosed by the vertical drop along the displacement of the channel heatable by the temperature of the cavity against the cavity wall in the molded part.

The three-dimensional determination of reinforcing fibers, such as glass fiber orientation, is well known in the art and is described, for example, in "Pipeline zur diridimensionalen auswertung und Visualisierung der Faserverteilung in glasfaserverstarkten Kunststoffteilen aus-Rontgen-Computertomografiedaten" A pipeline for two-dimensional evaluation and visualization of fiber distribution in glass fiber reinforced plastic material components from photographic data), J. Kastner et al. It is described in Gallen-Di.3.A.1. The fiber orientation is determined by a voxel of 8.6 탆 size. Further, the determination of the fiber distribution by the computer tomography and the determination of the orientation tensor can be performed according to the present invention with reference to the description of this document.

The process according to the invention can advantageously be carried out in particular in connection with step (c) so that one or more of the following conditions are met:

- θ _VT > θ _G or θ _VT > θ _K , preferably θ _VT -θ _G ≥≥10 _K or θ _VT -θ _K ≥≥10 _K , θ _G means the glass transition temperature of the amorphous thermoplastic molding compound and θ _K is the crystallization temperature of the partially crystalline thermoplastic molding compound,

-? _{VT =} ? _FM +/- 40K and / or

-θ _VT -θ _W ≥ 50K, preferably θ _VT -θ _W ≥100K.

θ _FM is the temperature of the molding compound entering the injection mold cavity.

The thermal behavior (melting point (? _FM ), melting enthalpy (? Hm), crystallization temperature (? _K ) and glass transition temperature (? _G )) was determined on granules with reference to ISO Standard 11357. Differential scanning calorimetry (DSC) was performed at a heating rate / cooling rate of 20 캜 / min.

Thus, channels that can be heated to one or more of the transition temperatures can be formed on one side or both sides of the injection mold cavity. In the case of the injection molding method, any injection mold formed of two or more partial molds is used, and when combined, the mold reflects the cavity and the shape of the molded part is manufactured. Thus, according to a preferred embodiment, there is provided one or more temperature-changing channels introduced into or formed in each cavity. In a preferred embodiment, the channels that can be heated by the mutated heat present on both sides of the wall of each of the injection molds are arranged to extend to coincide with the protrusions on the respective surfaces. In the case of this embodiment, the same volume area is temperature controlled in the injection mold by a channel that can be heated to a temperature which is disposed on both sides of the wall.

According to a further preferred embodiment, the sum of the areas of the channels which can be heated by one or more temperature changes (i.e. the total surface area of the region which can be temperature controlled on the surface of the cavity by means of channels or channels heatable by the temperature of transformation) 1 to 50%, preferably 3 to 30%, particularly preferably 4 to 20%, in particular 5 to 10% of the internal surface.

For example, a channel that can be heated to one or more temperatures is formed into a strip that is preferably heatable to a temperature having a constant width, and the width is preferably 0.2 to 30 mm, preferably 0.5 to 10 mm. However, the present invention is not limited thereto.

One possible embodiment of the present invention is an injection mold having one or more brake-thru. This breakthrough causes a gap to be created in the injection mold having the molded part to be manufactured, that is, the finished molded part having breakthrough, to cause a hole. These breakthroughs are not limited by their geometric structure, but have, for example, circular, elliptical, n-angular shapes, and n is a natural integer greater than or equal to three.

In embodiments where the injection mold has more than one break through, it is preferred that the channels that can be heated to one or more of the temperatures are formed in such a manner as to completely or at least partially extend in a circumferential form relative to the one or more brake throughs, Channels that can be heated by surrounding surrounding temperature are each formed on one side or both sides of the cavity of the injection mold wall.

According to this embodiment, it is preferable that when the channels which can be heated by one temperature change are formed around the brake-thru, the brake-thru is entirely surrounded by channels which can be heated by the corresponding temperature.

It is preferred that the at least one temperature-change channel formed in a manner that completely or at least partially extends in a circumferential form with respect to the at least one brake-thru has at least one connection in the inflow direction and at least one connection in the outflow direction. Preferably, the connection in the inflow direction continues to the gate position of the injection mold and / or the connection in the outflow direction continues to one or more overflow openings. In this embodiment, the channel that can be heated by the ambient temperature surrounding the breakthrough has two connections and the connection in the inlet direction corresponds to the main flow direction of the thermoplastic molding compound during the injection molding process in the breakthrough direction, Corresponds to the thermoplastic molding compound flow after flowing near the breakthrough. Each connecting portion of the channel heatable by the transforming heat is likewise formed into a region heatable by the transforming heat. Channels that can be heated by the transformer are configured in the case of brake-thru and connection areas.

At the connection, branching of channels which can be heated by the transforming heat is carried out in the region formed in the vicinity of the corresponding break-through. Elsewhere, the two partial arms of the channel, which can be heated by the thermocouple, are in turn connected to the connection in the outflow direction.

Particularly, the connecting portion in the inflow direction and the connecting portion in the outflow direction are arranged offset from each other at the breakthrough protrusion, preferably offset from each other by 120 DEG or more, and particularly offset from each other by 180 DEG +/- 10 DEG. The range of 180 DEG +/- 10 DEG includes all the angles in this region, specifically, exactly 180 DEG.

The connection in the inflow direction and the connection in the outflow direction, when the molded part to be manufactured has a main tensile load direction, i.e. the direction during which the molded part is permanently or at least temporarily used under tension and / or tensile loads, Each of which has a direction independent of each other in the breakthrough protrusion, which deviates from the main tensile load direction by 60 DEG or less, preferably 50 DEG C or less, more preferably 40 DEG C or less, particularly 30 DEG or less. Particularly preferably, this condition applies to both inflow and outflow. As a result, the reinforcing fibers in the breakthrough region can be essentially oriented, that is, in the direction of the main tensile load direction, in other words, anisotropic distribution in the direction of the main tensile load can be achieved according to the above definition. Thus, the orientation of the reinforcing fibers in the transverse direction with respect to the major tensile load direction can be essentially prevented in the location region of the temperature-changing channel or the temperature-changing channels. In this embodiment, significant enhancement of the molded part in the main tensile load direction can be achieved compared to the molded part produced from a conventional injection molding process.

The thermoplastic molding compound used in accordance with the process according to the invention is preferably formed from one or more thermoplastic matrix polymers or a mixture of two or more thermoplastic matrix polymers, wherein the reinforcing fibers are dispersed in the thermoplastic molding compound. In addition, the thermoplastic molding compound may contain conventional additives contained in thermoplastic molding compounds, examples of which include flame retardants, molding aids, and the like. The matrix polymer is preferably a polyamide comprising polyamide imide, polyetheramide and polyester amide; Polycarbonate; Polyolefins, in particular polyethylene, polypropylene and polystyrene or polyvinyl chloride (PVC); Polyacrylates, especially polyacrylic esters, such as poly-methyl (meth) acrylate; Acrylonitrile-butadiene-styrene copolymers, acrylonitrile-styrene copolymers; Polyesters, especially polyethylene terephthalate, polybutylene terephthalate or polycyclohexylene terephthalate, polysulfone (especially PSU, PESU, PPSU type), polyphenylene sulfide; Polyethers, especially polyoxymethylene, polyphenylene ethers and polyphenylene oxides, liquid-crystalline polymers; Polyether ketones; Polyether ether ketone; Polyimide; Polyester imide, polyetheresteramide; Polyurethanes, in particular TPU or PUR type; Polysiloxanes; Celluloid, and mixtures or combinations thereof.

Preferred reinforcing fibers are preferably selected from the group consisting of glass fibers, carbon fibers (carbon fibers, graphite fibers), aramid fibers and whiskers. Preferably, glass fibers and carbon fibers are used.

The reinforcing fibers, in particular the glass fibers, are preferably incorporated into the molding compound in the form of an endless strand or cut, in particular in the form of short fibers, for example short glass fibers (cut glass).

In the case of short fibers, especially short glass fibers, these fibers added to the molding compound have a preferred length of 0.2 mm to 20 mm, preferably 1 to 6 mm, in particular 2.5 mm.

Preferably, the reinforcing fibers are sized and / or tackified.

In general, the glass fibers may have a circular cross section or a non-circular cross section, and mixtures of such systems may also be used.

Preferably, in the case of round glass fibers, those having a diameter of 5 to 20 占 퐉, preferably 6 to 15 占 퐉, particularly preferably 7 to 12 占 퐉 are used.

Preferably, for flat fibers, the ratio of the transverse axis (the major transverse axis to the auxiliary transverse axis is perpendicular to each other) is in the range of 2 or more, particularly 2.8 to 4.5, and their smaller transverse axis is? 4 Mu m.

The glass fibers are preferably made of E-glass. However, all other types of glass fibers can be used, for example A-, C-, D-, M-, S-, R- glass fibers or any mixture thereof or mixtures with E-glass fibers . The glass fibers may be added as infinite or cut glass fibers, and the fibers may be treated with an appropriate sizing system and an adhesive system, or an adhesive system based on, for example, silane, aminosilane or epoxy silane.

Glass fibers can be partially or wholly replaced with whiskers. This is in the form of a regular polygonal cross-section made of whiskers, needle-shaped crystals, in particular metals, oxides, boron, carbides, nitrides, polytitanates, carbon and the like, for example potassium citrate-, aluminum oxide-, silicon carbide whiskers It must be understood. Generally, the whiskers have a diameter in the range of 0.1 to 10 mu m and a length in the range of mm to cm. At the same time, they have a high tensile strength. Whiskers can be produced by deposition from a VS mechanism in solid or by deposition from a trinary system (VLS mechanism).

The molding compound used in the injection molding method according to the present invention may contain, alone or in combination with other reinforcing fibers, or carbon fibers. Carbon fibers are reinforcing fibers that are industrially produced from carbon-containing starting materials that are converted to carbon having a graphite-like arrangement by pyrolysis (oxidation and carbonization). Anisotropic carbon fibers exhibit high strength and stiffness and at the same time exhibit a low elongation at break in the axial direction.

The carbon fibers are preferably used as carbon fiber bundles consisting of several hundred to hundred thousand carbon fibers, so-called individual filaments, having a diameter of 5 to 9 탆, a tensile strength of 1,000 to 7,000 MPa and an elasticity of 200 to 700 GPa. Generally, 1,000 to 24,000 individual filaments are combined to form a wound multi-filament yarn (infinite carbon fiber bundle, roving). For example, further processing to form a fabric semi-finished product, such as a woven fabric, a plaited fabric, or a multiaxial fabric, may be applied to a loom, a plaiting machine, A prepreg unit, a strand-drawing unit (pultrusion unit), or a winding machine in the field of producing a multiaxial knitting machine or a fiber-reinforced plastic material, As the short cut fibers, the carbon fibers can be directly mixed with the polymer or molding compound and can be processed to form the plastic material component through an extruder and an injection molding machine.

The weight ratio of the reinforcing fibers in the thermoplastic molding compound is preferably 5 to 80% by weight, preferably 20 to 70% by weight and particularly preferably 25 to 65% by weight.

The thermoplastic molding compound may be formed from the above-mentioned components and may also contain conventional additives such as, for example, particulate fillers and pigments, stabilizers (heat stabilizers and light stabilizers, antioxidants), UV absorbers, A lubricant, a releasing agent, a plasticizer, a radical collector, an antistatic agent, a flame retardant, a colorant and a marking means, a nanoparticle in the form of a plate, a silicate layer, a conductive additive such as Carbon black, graphite powder or carbon nanofibers, additives for improving thermal conductivity, such as boron nitride and aluminum nitride are also possible.

The particulate filler is preferably selected from the group consisting of talc, mica, silicates, quartz, titanium dioxide, wollastonite, kaolin, amorphous silicic acid, magnesium carbonate, magnesium hydroxide, chalk, lime, feldspar, Flakes, permanent magnets or magnetic metal compounds and / or alloys, pigments, in particular barium sulphate, titanium dioxide, zinc oxide, zinc sulphide, iron oxide, copper chromate or mixtures thereof. Fillers can also be surface treated.

The molding compound preferably used in the injection molding method according to the present invention is preferably used in the case where the general procedural shear rate (shear viscosity) is 100 to 10,000 sec ^-1 , particularly 1,000 to 10,000 sec ^-1 , preferably according to ISO 11443 Measured in the range of 10 to 10,000 Pas, particularly preferably in the range of 20 to 3,000 Pas and very particularly preferably in the range of 30 to 1,000 Pas. The temperature at which the melt viscosity is determined corresponds to the general measured temperature of the molding compound relative to the MVR measurement (melt volume flow) according to ISO 1133 as indicated in the manufacturer &apos; s data sheet. If this is not possible, a measuring temperature of 5 to 100 DEG C, preferably 10 to 40 DEG C, higher than the melting temperature (partial crystalline plastic material matrix) of the molding compound or higher than the glass transition temperature (amorphous plastic material matrix) is selected . For example, a polyamide molding compound filled with 30 to 60% by weight of glass fibers with PA 6T / 6I (70:30) can be measured at 335 to 355 占 폚.

Thus, while overfilling, filling, or partially filling the injection mold, the melt viscosity of the thermoplastic molding compound at the injection location into the injection mold cavity can be adjusted by the choice of? _FM , preferably from 10 to 8,000 Pas, Preferably 50 to 5,000 Pas. Preferably, the pressure at which the thermoplastic molding compound is injected into the injection mold cavity is between 50 and 2,000 bar.

The present invention also relates to a molded part formed from a thermoplastic molding compound filled with reinforcing fibers. Therefore, the molded part can be manufactured according to the above method. The shaped part according to the invention is characterized in that the reinforcing fibers with intrinsic anisotropic orientation of the reinforcing fibers in the region produced during the manufacturing process are subjected to the trajectory of the channel which can be heated by one or more temperatures with the area of the injection mold, Lt; / RTI &gt;

As a result, significantly increased tensile strength is achieved compared to other identical components made with conventional injection molding having the same gate position (i.e., without thermo-heating in the above sense).

The orientation of the reinforcing fibers is defined by the following orientation tensor (a _ij ) of the group of n reinforcing fibers contained in one finite volume element,

The element a _ij is defined as follows,

The orientation of the fibers is determined by the diagonal elements a ₁₁ , a ₂₂ and a ₃₃ of the orientation tensor (a _ij )

또는

는 각각 k번째 섬유에 평행하게 연장되는 길이 1의 벡터

성분을 나타내며,

or

Lt; RTI ID = 0.0 &gt; A vector of length 1 extending in parallel

Lt; / RTI &gt;

는 로컬 좌표계에서 하나 이상의 변온으로 가열 가능한 채널 영역에서 각각의 고려되는 유한 체적 요소를 나타내며,vector

Represents each considered finite volume element in the channel region that is heatable to one or more of the temperature changes in the local coordinate system,

The x-axis is fixed in each tangential direction to the trajectory of the channel which can be heated to one or more of the thermo-energies in each considered finite volume element,

The y-axis is oriented perpendicular to x,

The z-axis is oriented perpendicular to x and y,

The value of the element a ₁₁ of the orientation tensor (a _ij ) in each given finite volume element is 0.5 or more, preferably 0.5 to 0.98, more preferably 0.6 to 0.95, more preferably 0.65 to 0.9, especially 0.7 to 0.85 , An essentially anisotropic orientation is produced.

With respect to the additional definition of n or the additional standard coordinates y and z, the above given description is referred to.

In particular, the molded part according to the invention is selected from the group consisting of structural components with high mechanical properties and functional components with high dimensional accuracy.

The present invention relates to an injection mold for producing a molded part made of a thermoplastic molding compound comprising reinforcing fibers by injection molding and which comprises two parts assembled to surround a cavity for reproducing the external geometry of the molded part to be manufactured At least one injection port for filling the cavity with a thermoplastic molding compound that is present in the plasticized state and contains the reinforcing fibers is provided in one or more partial molds (gate positions), and one or more injection molds And a channel that is heatable to one or more of the transition temperatures formed in the mold wall defining the partial mold or cavity. The injection mold according to the present invention can be used in the above-described method according to the present invention for producing a molded part, in particular, by injection molding. Any description of the specific configuration of the injection mold, and in particular at least the channels which can be heated by the temperature change, also applies to the injection mold provided in accordance with the invention.

A preferred embodiment of the injection mold has one or more breakthroughs that generate a gap in the molded part from which all of the partial molds are made, wherein the channel heatable by one or more of the temperatures is completely or at least partially extended And has a connection portion in the inflow direction and a connection portion in the outflow direction and the connection portion in the inflow direction and the connection portion in the outflow direction are offset from each other at the breakthrough protrusion portion, Offset, and in particular disposed on the opposite side of the brake-thru. The range of 180 DEG +/- 10 DEG includes any angle within this range, and specifically, it is precisely 180 DEG.

The connecting portion in the inflow direction and the connecting portion in the outflow direction are respectively formed at the breakthrough protrusions by 60 degrees or less, preferably 50 degrees or less, more preferably 50 degrees or less from the main tensile load direction, Is less than 40 DEG, particularly less than 30 DEG.

Preferably, the injection mold has one or more overflow openings in fluid communication with the cavity such that, when the injection mold is overfilled, the thermoplastic molding compound is injected into the cavity, overflow opening, and more preferably into the respective overflow cavity It can flow into the opening.

According to a further preferred embodiment, a channel which can be heated by one or more of the transition temperatures starts at the gate position of the injection mold, and preferably ends at one or more overflow openings.

It is preferable that the above-described connecting portion is formed up to the gate position of the injection mold; Alternatively or additionally, it may be possible that the connection continues in the outflow direction to the overflow opening.

According to a further preferred embodiment, the sum of the channel areas heatable by one or more of the temperature changes is in the range of 1 to 50%, preferably 3 to 30%, particularly preferably 4 to 20%, particularly preferably 5 to 20%, of the internal surface of the injection mold cavity To 10%.

Alternatively or additionally, the channels which can be heated by one or more of the transformations are formed into strips which can be heated to a temperature preferably having a constant width, and the width is preferably 0.2 to 30 mm, preferably 0.5 to 10 mm.

It is further preferable that the injection mold according to the present invention has a cooling unit capable of cooling the wall defining the injection mold cavity. With this cooling unit, the entire wall of the injection mold cavity can be cooled, in particular, the cooling and solidification of the thermoplastic molding compound placed in the cavity, and thus the entire final molding process, can be significantly accelerated.

The present invention will be described in more detail with reference to the following embodiments, but the present invention is not limited to the embodiments.

The method according to the invention enables the orientation of the fibers in the molded part to be influenced and to be designed essentially anisotropically within a certain area.

Using the method according to the invention, it is possible to ensure that the molded part (s) are aligned such that the major fiber orientation (x-direction fiber orientation tensor) in all mechanically related regions is matched to the maximum principal stress vector (the intended load of the molded part in the x- Can be designed at the same position of the gate position. According to the invention, the fiber orientation corresponds to no more than 50%, preferably no more than 60% and particularly preferably no more than 65 or no more than 70% of the total thickness of the test piece in the main stress axis (X-X) direction. For conventional injection molding and similar gate locations, the fiber orientation tensor is centrally located over the thickness of the specimen of less than 35% in the direction of the principal stress vector. An alignment of only slightly over 40% in the direction of the principal stress vector is achieved in the edge region.

In most cases, if the orientation of the fibers deviates from the main stress axis, as in the case of conventional injection molding, the potential for material strength can not be fully exploited. This means that component failure occurs even at low stress levels.

Using the method according to the invention, a significantly higher strength can be achieved prior to the destruction of the molded part, compared to the conventional injection molding method (same gate position) The direction of the stress vector. Therefore, the strength is obtained in the range of 40 to 100%, preferably in the range of 50 to 80%, as compared with the conventional injection molding.

According to the present invention, a mold is used in which one or more mold walls start at the gate position and further heatable elements continue to the area of the mold wall where the fiber orientation is affected. The mold wall area is correlated to the location (s) of the component's highest stress (s) under a given application load. Preferably, the heatable element continues from this region to the overflow cavity adjacent to the mold cavity. For each mold wall area, the additional heating element accounts for less than 50%, preferably less than 30% and particularly preferably less than 20%. The width of the heating element is generally between 0.5 and 10 mm and may be constant or variable with respect to the path of the mold wall. For length, the heating element describes a path on the surface of the mold wall that can be freely selected and preferably extends from the gate to the overflow cavity. The path of one or more auxiliary heating elements within the mold wall must be designed to correspond to each operation. The additional heating allows the plastic material molding compound in the mold cavity to remain in the heating zone or at the end of the filling step to flow in a zone that is still heatable, i.e. in a heatable channel, with the remaining molding compound already solidified or at least having a high viscosity .

Channels that can be heated by the thermocouple are still of great significance at the beginning of the injection, but the melt is actually pushed into the cavity in a manner indistinguishable from conventional injection molding. Only at the end of the pressure maintenance step, the melt flow is specifically heated through the area of the mold cavity where it is heated to the additional heating element of the mold cavity and is actually heated, particularly to the overflow cavity.

The strength to fracture is improved up to 100% by the fiber orientation in the main stress axis direction of the molded part which is changed with respect to the conventional injection molding method.

The thick-film heating technique for heating the channel is preferably used because the method with channels that can be heated by the transformer requires very local heating and independent design.

The method of making a reinforced molded part may comprise the steps of, for example, injecting a plastic material molding compound having a fibrous reinforcement (preferably 20 to 70 wt%) into the mold cavity and exposing at least one additional heating Less than 50% of the wall area is heated by the element, which is in the form of a strip of 0.5 to 10 mm width extending from the gate position projecting on the surface of the mold wall to the overflow cavity, except for areas with additional heating elements The mold is temperature controlled to a temperature lower than the solidification temperature of the plastic material and this temperature remains substantially constant during the entire injection molding cycle (preferred temperature control (1)), and the mold area on the additional heating element The temperature of the plastic material is maintained at a temperature higher than the solidification temperature of the plastic material, The compound may still flow from the end of the available channel internal pressure holding step of heating the byeonon and becomes a melt of the excess poured into an overflow cavity.

The path of the one or more additional heating elements deviates from the direction of the initial melt flow in one or more of the areas, i.e. the direction of the melt flow caused by the gate position.

Figure 1 shows a rectangular shaped injection molding component.
Figure 2 shows the vector stress distribution for the same components.
Figure 3 schematically illustrates an injection molding method for the production of molded parts according to Figures 1 and 2, as is known in the art.
Fig. 4 shows the final product of the injection molding process shown in Fig. 3 (the same cross section as Fig. 2).
FIG. 5A is a reduced representation of FIG. 4, and FIG. 5B is a view corresponding to the reduced view of FIG.
6 illustrates an injection mold according to an embodiment of the present invention.
Fig. 7 shows the same injection mold as shown in Fig.
Figure 8 shows the respective volume elements used in the grid.
Figure 9 shows a comparison of the filling of the injection mold and the simulation of the filling method as shown in Figure 3, in accordance with the method according to the prior art (Figure 9a).
Figures 10 a) and 10 b) show the temperature profile taking place in the thermoplastic molding compound during the injection molding process.
Figure 11 shows a rate plot in which the thermoplastic molding compound is retained within the injection mold cavity.
Figure 12 shows the fiber distribution reproduced by the implementation of the method according to an embodiment of the present invention.
Figs. 13 a) and 13 b) are similar to Figs. 5 a) and 5 b), again comparing the tensile force generated in a molded part produced during a tensile load and the fiber distribution in a component produced by the method according to the invention .
Figure 14 shows the fiber distribution that occurs during the method according to the present invention, referred to herein as the fiber orientation method.
15 shows the results of a simulation test on the component (Fig. 15a) manufactured according to the known technique and the component manufactured according to the method according to the invention (Fig. 15b)).

Figure 1 shows a rectangular shaped injection molding component which is used in the following tests in the embodiment. The component has a length of 100 mm, a width of 75 mm and a thickness of 3 mm, which protrude in the image direction. A circular brake through D having a diameter of 30 mm is introduced into the center of the component.

1 shows the stress distribution occurring in the component when the force F (in the case of 10 kN) is applied in the longitudinal direction of the component. Whereby the component can be fixed to one side (left side of Fig. 1).

It can be seen that the maximum stress is directly generated in the boring perpendicular to the tension direction. In particular, these positions allow a breaking point within the component.

Figure 2 also shows the vector stress distribution for the same components. In Fig. 2, the stress at each of the illustrated positions is represented by the principal action component (arrow direction) and their absolute value (arrow size) symbol.

The test of the components according to Figures 1 and 2 (all additional tests shown in Figures 3 to 15) were carried out on a 50% by weight solution having a circular cross section with a melting point of 325 캜 (10 탆 in cross section and 200 탆 in length) (A finite element method using a molding compound made of polyamide 6T / 6I (molar ratio 70:30) reinforced with glass fibers).

Figure 3 schematically illustrates an injection molding method for the production of molded parts according to Figures 1 and 2, as is known in the art. The cavity K is filled with the thermoplastic compound in a molten state including glass fiber through the gate position A. 3, the cavity K is not completely filled with the thermoplastic molding compound, and the thermoplastic molding compound already partially flows from the gate position A about the brake through D. Although the respective flow fronts of the thermoplastic molding compounds have not yet flowed completely together with respect to the brake through D, in the state shown in Fig. 3, the confluence of the thermoplastic molding compounds shows an imminent state.

Fig. 4 shows the final product of the injection molding process shown in Fig. 3 (the same cross section as Fig. 2). After filling the injection mold cavity K completely, a molded part can be obtained which, as shown in Fig. 3, produces a bond line WL after it has flowed together in the two front regions of the thermoplastic molding compound. Figure 4 shows the orientation of the reinforcing fibers contained in the thermoplastic molding compound. It can be seen that the reinforcing fibers (in this case glass fibers) are distributed anisotropically away from the break through D in the splicing line WL region. When the two flow wires flow together, the glass fibers are oriented parallel to each other.

However, the distribution of such glass fibers in the molded part is very disadvantageous. This is illustrated with reference to the comparison of Figures 5A and 5B. FIG. 5A is a reduced representation of FIG. 4, and FIG. 5B is a view corresponding to the reduced view of FIG. It can be seen that the fiber distribution generated in the region of the bonding line WL is ineffective in absorbing the maximum possible tensile stress occurring in this region. For such a purpose, a tensile force or a parallel fiber distribution is required. However, this is not possible with the conventional injection molding method. Conventional methods result in the orientation of glass fibers or reinforcing fibers that are essentially perpendicular to tensile stress. Therefore, the bonding line WL region is not suitable for absorbing the tensile force generated, and the obtained molded part exhibits a predetermined breaking point.

FIG. 6 illustrates an injection mold according to an embodiment of the present invention in which a specific anisotropic distribution of reinforcing fibers, such as glass fibers, through an injection mold is made possible in the component. The injection mold may enable the longitudinal and transverse directions of the molded component at the side (nozzle side) of the injection mold. Thus, the depth dimension, i. E. The thickness of the component, is shown extending downward in accordance with the figure.

The injection mold may have a breakthrough D that can cause a gap in the molded part to be manufactured accordingly. Using such an injection mold, a shape according to the same components as those shown in Figs. 1 to 5 can be produced.

까지 유도되어, 초과량의 열가소성 성형 화합물이 사출 금형으로부터 빠져나올 수 있도록 한다. 이러한 사출 금형을 이용하여, 이후에 상세하게 설명하는 바와 같이 본 발명에 따른 방법을 구현할 수 있다. 이 사출 금형에 대한 설명은 하기의 모든 실시예에 적용될 수 있다.One or more walls defining the injection mold cavity may be provided with a channel VK which can be heated by the temperature change in the case of both walls, i.e., the front side (the nozzle side, the side with the gate position) and the rear side (the exhaust side) The wall defining the mold cavity can be locally heated in the channel. As in the example shown in Fig. 6, the channel VK, which can be heated by the temperature change, can be started at the gate position A where the cavity can be filled with the thermoplastic molding compound. The gate position A can be selected as shown in Fig. As shown in FIG. 6, the channels that can be heated by the temperature change are selected to have a width of 2.5 mm, and can have the same width over the entire path. In Fig. 6, the channel which can be heated by the temperature change is guided rightward when viewed from the gate position, and the angle maintained with respect to the longitudinal side of the injection mold is 30 deg. Then, the possible channel VK heated byeonon is deviating into the supply pipe F _1, wherein the supply pipe F ₁ may be the flow towards the break-through D. The channels which can be heated by the temperature change have a circular shape along the entire brake through D and converge at the discharge F ₂ . Inlet F ₁ and The outlet F ₂ can be placed on the opposite side facing exactly. The channels which can be heated by the temperature change are branched in the region of the brake through D and are annularly centered around the brake through D. The channel VK, which can be heated by the above-mentioned temperature change, has an overflow opening (not shown) introduced into the injection mold wall

To allow excess amounts of the thermoplastic molding compound to escape from the injection mold. Using such an injection mold, the method according to the present invention can be implemented as will be described in detail later. The description of this injection mold can be applied to all of the following embodiments.

내에 배치될 수 있다. 사출 금형의 게이트 위치에는 이른바 핫 채널(hot channel)("핫 러너"; "hot runner", HR)이 설치되어 있고, 상기 핫 채널을 통하여 열가소성 성형 화합물이 사출 금형에 공급될 수 있다. 변온으로 가열 가능한 채널 VK는 사출 금형의 나머지 영역과 비교하여 어두운 색으로 표시된다. 상기 사출 금형의 경로는 도 6에 표시된 경로와 동일할 수 있다.Fig. 7 shows the same injection mold as shown in Fig. 6, in which the overflow capacity Gt; a &lt; / RTI &gt; collection reservoir for the thermoplastic molding compound,

As shown in FIG. A so-called hot channel ("hot runner &quot;, HR) is installed at the gate position of the injection mold, and the thermoplastic molding compound can be supplied to the injection mold via the hot channel. The channel VK, which can be heated by the temperature change, is displayed in dark color as compared with the remaining area of the injection mold. The path of the injection mold may be the same as the path shown in Fig.

It is based on the following assumptions:

Molding compound comprising reinforcing fibers:

The filled with glass fiber (filled 50%, glass fiber diameter 10㎛, glass fiber length 200㎛), the melting point 325 ℃) polyamide 6T / 6I (70:30), crystallization temperature: θ _K = 285 ℃, MVR (340 ℃ / 21.6kg) = 100cm 3/10 min, melt viscosity (340 ℃, shear rate of 1,000Hz) = 230Pas.

Parameters:

* Temperature of remaining mold wall: θ _W = 150 ° C

Molding compound temperature during filling and filling: θ _FM = 340 ° C.

* The temperature of the heat-exchanging channel according to the trajectory during filling and over-filling in the holding pressure stage: θ _VT = 305 ° C.

* Injection speed during filling (flow rate): 15 cm ³ / s

* Switching point to injection pressure: As soon as injection pressure of 25 MPa is reached, switching from flow control filling to pressure control

* Retention pressure in the first part of the retention pressure phase: maintain pressure of 60 MPa for 10 seconds

* In the second part of the retention pressure phase, if a residence pressure of 120 MPa is applied for 6 seconds, the plastic material melt (molding compound) is pressed into the overflow capacity along the trajectory

* Retention pressure in the third part of the retention pressure phase: 2.5 Mpa pressure applied for 1 s (total retention pressure step lasts 17 s)

* Filling time: 1.6 seconds (volume filling of 99% without overflow capacity)

* Injection pressure at filling of 99% volume: 25Mpa

* Volume of overflow capacity: 8.8 cm ³ (filled at the second residence pressure stage)

* Cavity volume: 20.38 cm ³

Volume ratio of filled cavity: 43.2%

For the following simulation calculation, the volume of the injection mold cavity was actually subdivided into the grids shown in FIG. 7, and the respective volume elements used in the grid were described in detail in FIG.

Figure 9 shows a comparison of the filling of the injection mold and the simulation of the filling method as shown in Figure 3, in accordance with the method according to the prior art (Figure 9a). FIG. 9B shows a filling process by the injection mold according to the present invention as shown in FIG. 6 or FIG. It can be confirmed that the filling pattern of the injection mold with the thermoplastic molding compound is essentially the same. In the injection molding method of the injection mold according to the present invention (see FIG. 9B), a flow to break through D occurs and here also the confluence of the thermoplastic molding compound takes place on the side of break through D in the direction away from gate position A. Figures 10 a) and 10 b) show the temperature profile taking place in the thermoplastic molding compound during the injection molding process. Figure 10 a) shows different cross-sectional profiles immediately after fully filling the injection mold or during overfilling of the injection mold. (Not shown in Fig. 10A) in which the temperature control of the injection molding metal molds on both sides is carried out by a channel heatable by the temperature change), the temperature is higher than the melt transition temperature (the region represented by Region I in Fig. 10A) Able to know. The temperature of the thermoplastic molding compound in the remaining region (region II) is already below the melting transition temperature. After the injection mold has been completely filled, the area carried out through the channels which can only be heated by the temperature of the transition may still be in a molten state, i.e. by a further injection of the thermoplastic molding compound through the hot runner HR. At the gate position A, the specific flow of the thermoplastic molding compound can be carried out directly at the location where channels or channels that can be heated by the temperature change are formed.

Figure 10 b) shows an envelope (so-called contour plot) in which the temperature of the thermoplastic molding compound is still 305 ° C in the selected embodiment. It can be confirmed that these regions are exclusively present at positions where channels capable of being heated by the temperature change are formed. The remaining area of the injection mold can not have such a value without further heating, and the temperature of these areas is about 150 ° C.

Figure 11 shows a rate plot in which the thermoplastic molding compound is retained within the injection mold cavity. The velocity profile indicates the vector, the arrow indicates the direction of flow, and the arrow indicates the length corresponds to the velocity.

11 (a) shows the velocity profile of an injection mold with no channels heatable by temperature. It can be seen that the flow direction of the thermoplastic molding compound is essentially symmetrical until the injection mold is completely filled.

11 (b) shows a phenomenon that occurs when the injection mold is partially overfilled. It is demonstrated that the flow of the thermoplastic molding compound is exclusively carried out exclusively in a zone where it can be heated by the temperature of the transition, and that the flow of the thermoplastic molding compound is essentially flowed along the defined trajectory through the channel heatable by the temperature.

Figure 12 shows the fiber distribution reproduced by the implementation of the method according to an embodiment of the present invention. It can be seen that the fiber distribution in the temperature-controlled channel region has an inherently anisotropic configuration and flows along the locus of the channel which can be heated by the temperature change.

Figs. 13 a) and 13 b) are similar to Figs. 5 a) and 5 b), again comparing the tensile force generated in a molded part produced during a tensile load and the fiber distribution in a component produced by the method according to the invention . It can be confirmed that the fiber orientation 13a is accurately performed along the tensile force at the position where the maximum tensile force 13b is generated. Therefore, the fibers can absorb the generated tensile stress optimally.

Figure 14 shows the fiber distribution that occurs during the method according to the present invention, referred to herein as the fiber orientation method. The calculation of the fiber distribution can be carried out by a position which is carried out in the region of the channel which can be heated by the temperature of the opposite side of the gate position. The black point shown on the left side of FIG. 14 indicates the crystal position. At this location, the considered x-component produced by the local coordinate system, that is, the tangent to the trajectory of the temperature-transition channel, coincides with the direction of the main tensile load. According to the conventional manufacturing method, it is confirmed that a fiber distribution which is isotropic is essentially applied to the fiber orientation in the x- or y-direction. The fibers are mainly oriented in the y-direction at this location, while the corresponding orientation of the fibers in the x-direction has only a subordinate meaning.

As can be seen from Fig. 14, the method according to the invention can achieve that the fiber distribution in the x-direction is clearly at the top, that is, the fibers in the measured in the x-direction have a significantly anisotropic distribution , The major part of the fibers being oriented mainly in the x-direction. Thus, the fibers at this position are optimally oriented to absorb the tensile forces generated in the component.

15 shows the results of a simulation test on the component (Fig. 15a) manufactured according to the known technique and the component manufactured according to the method according to the invention (Fig. 15b)). In this test, as shown in Fig. 1, a tensile load of 1,350 N is applied to the narrow side of the molded part, and the force indicated on the molded part is applied.

The standard strain according to FIG. 15 a) and the thermoform strain with the aligned line according to FIG. 15 b) with the bond line were compared with each other by finite element (FE) calculation. The FE calculation was implemented considering the anisotropic material model with fiber orientation and failure criterion in the injection molding simulation. On one side a sheet with holes (100x75x3 mm wide, 30 mm in diameter) was fixed in all directions, while the other side was externally applied with a force perpendicular to the surface. The results show the breakthrough of the standard deformation model with 7,965N seams and the thermodynamic deformation model with the fine seams of 12,015N. This represents an improvement of 51%.

Both FIGS. 15A and 15B show a contour line diagram of the failure criterion used while the load is applied at 1,350N. The legend represents the reciprocal of the safety factor. For example, a value of 0.112 means safety against fracture due to a load of 1 / 0.112 = 8.9. The standard deformation with a joining line indicates that the joining line is a potential failure region, while the thermoforming with refined joining lines no longer exhibits a joining line, but rather two entire notch regions represent potential failure regions.

: 나머지 금형 벽
F₁: 유입; 브레이크스루 D를 중심으로 원으로 유도되는 변온 채널로 플라스틱 물질 용융물을 공급하는 변온 채널의 일부
F₂: 유출; 브레이크스루 D를 중심으로 원으로 유도되는 변온 채널에서 플라스틱 물질 용융물을 받아 변온 채널의 일부분을 통과하여 오버플로우

에 공급하는 변온 채널의 일부

: 오버플로우 개구

: 오버플로우 용량
HR: 가열 채널D: Break through in component
F: force applied to the component
K: Injection mold cavity
A: Gate position
WL: Crimp line
VK: Transient channel

: Remaining mold wall
F ₁ : Inflow; A part of the temperature-dependent channel that supplies the melted plastic material to the circulation-induced temperature channel centered on the brake through D
F ₂ : effluent; The melted plastic material is received in the circularly-directed thermo-chan- nel centered on the brake-thru D,

A part of the temperature-changing channel

: Overflow opening

: Overflow capacity
HR: heating channel

Claims (24)

As a method for producing a molded part from a thermoplastic molding compound containing reinforcing fibers by injection molding,
The injection mold cavity is heated to the prescribed temperature &amp;thetas; _FM , filled in the plasticized state to the filling level defined by the thermoplastic molding compound containing the reinforcing fibers, completely filled, partially filled, The mold cavity has one or more walls having channels that can be heated by one or more variotherms extending along the locus,
The region of the injection mold having one or more temperature change channels permanently or at least temporarily temporally is set to the temperature &amp;thetas; _VT and the remaining region of the wall of the injection mold is at a temperature &lt; RTI ID = is set to be _W, θ _W <θ _VT,
After the filler is filled to the specified filling level, fully filled, or partially filled, the thermoplastic molding compound containing the reinforcing fibers is cooled until solidified,
And the solidified molded part is released from the injection mold. The method according to claim 1,
Each of the overflow cavities being in fluidic communication with an injection mold cavity and having one or more overflow openings that are overfilled with one or more heat transfer channels, Starting at the gate position of the injection mold and leading to the at least one overflow opening such that when the injection mold is overfilled, the thermoplastic molding compound can escape out of the injection mold cavity and through each of the overflow openings, Into the cavity. 3. The method according to claim 1 or 2,
Overfilling of the injection mold is performed
5 to 100% by volume, preferably 10 to 70% by volume and particularly preferably 15 to 50% by volume of the injection mold cavity is overfilled,
After full filling, a waiting time of 2 to 60 seconds is maintained before over filling begins and during the waiting time the temperature &lt; RTI ID = 0.0 &gt; _{VT &lt; /} RTI &gt; in the region of the injection mold with one or more temperature- The temperature &lt; RTI ID = 0.0 &gt; _W &lt; / RTI &gt; in the remaining region on the wall of the injection mold Lowered / lowered,
And the filling lasts for a time range of 2 to 60 seconds. 4. The method according to any one of claims 1 to 3,
Adjustment of the orientation of the reinforcing fibers in the thermoplastic molding compound is performed by adjusting the temperature difference [theta] _W < [theta] _VT , and anisotropic cultivation of the reinforcing fibers is essentially achieved along the trajectory of the channel heatable by one or more temperatures &Lt; / RTI &gt; 5. The method of claim 4,
The orientation of the reinforcing fibers is defined by the following orientation tensor (a _ij ) of the group of n reinforcing fibers contained in one finite volume element,

The element a _ij is defined as follows,

The orientation of the fibers is determined by the diagonal elements a ₁₁ , a ₂₂ and a ₃₃ of the orientation tensor (a _ij )

or

Lt; RTI ID = 0.0 &gt; A vector of length 1 extending in parallel

Lt; / RTI &gt;

vector

Represents each considered finite volume element in the channel region that is heatable to one or more of the temperature changes in the local coordinate system,
The x-axis is fixed in each tangential direction to the trajectory of the channel which can be heated to one or more of the thermo-energies in each considered finite volume element,
The y-axis is oriented perpendicular to x,
The z-axis is oriented perpendicular to x and y,
The value of the element a ₁₁ of the orientation tensor (a _ij ) in each given finite volume element is 0.5 or more, preferably 0.5 to 0.98, more preferably 0.6 to 0.95, more preferably 0.65 to 0.9, especially 0.7 to 0.85 , An essentially anisotropic orientation is produced. 6. The method according to any one of claims 1 to 5,
θ _VT > θ _G or θ _VT > θ _K , preferably θ _VT -θ _G ≥10 _K or θ _VT -θ _K ≥10 _K , θ _G is the glass transition temperature of the amorphous thermoplastic molding compound and θ _K is the crystallization temperature of the partially crystalline thermoplastic molding compound,
θ _{VT =} θ _FM ± 40 K and / or
? _VT- ? _W ? 50K, preferably? _VT- ? _W ? 100K. 7. The method according to any one of claims 1 to 6,
Characterized in that a channel which is heatable by one or more temperature changes is formed on one side or both sides of the cavity of the injection mold wall. 8. The method according to any one of claims 1 to 7,
Characterized in that the sum of the channel regions heatable by one or more of the temperature changes is comprised of 1 to 50%, preferably 3 to 30%, particularly preferably 4 to 20%, in particular 5 to 10%, of the inner surface of the injection mold cavity . 9. The method according to any one of claims 1 to 8,
Characterized in that it has at least one breakthrough which generates a gap in the molded part from which the injection mold is manufactured, said breakthrough having, for example, a circular, elliptic, n-angular shape, , Way. 10. The method according to any one of claims 1 to 9,
A channel which is heatable by one or more of the transforming temperatures is formed in such a way that it is wholly or at least partly extended in a circumferential form with respect to one or more breakthroughs, preferably each breakthrough, Each being formed on one side or both sides of the cavity of the injection mold wall. 11. The method of claim 10,
Characterized in that at least one transition channel formed in a completely or at least partially extending manner in a circumferential form with respect to the at least one brake-thru has at least one connection in the inflow direction and at least one connection in the outflow direction, / RTI &gt; continuing to the gate position of the injection mold / continuing or the connection in the outflow direction continuing to at least one overflow opening. 12. The method of claim 11,
The connecting portion in the inflow direction and the connecting portion in the outflow direction are arranged offset from each other at the breakthrough protrusions, preferably offset from each other by 120 DEG or more, and particularly offset from each other by 180 DEG +/- 10 DEG How to. 13. The method according to claim 11 or 12,
The joint portions in the inflow direction and the joint portions in the outflow direction each have an independent direction from each other at the breakthrough protrusions, which is not more than 60 DEG from the main tensile load direction, Is less than 50 DEG, more preferably less than 40 DEG, especially less than 30 DEG. 14. The method according to any one of claims 1 to 13,
a) the thermoplastic molding compound comprises or consists of one or more thermoplastic matrix polymers or a mixture of two or more thermoplastic matrix polymers, wherein the reinforcing fibers are present in a dispersed state in the thermoplastic molding compound, and wherein the one or more matrix polymers are Polyamides including polyamide imides, polyether amides and polyester amides; Polycarbonate; Polyolefins, in particular polyethylene, polypropylene and polystyrene or polyvinyl chloride (PVC); Polyacrylates, especially polyacrylic esters, such as poly-methyl (meth) acrylate; Acrylonitrile-butadiene-styrene copolymers, acrylonitrile-styrene copolymers; Polyesters, especially polyethylene terephthalate, polybutylene terephthalate or polycyclohexylene terephthalate, polysulfone (especially PSU, PESU, PPSU type), polyphenylene sulfide; Polyethers, especially polyoxymethylene, polyphenylene ethers and polyphenylene oxides, liquid-crystalline polymers; Polyether ketones; Polyether ether ketone; Polyimide; Polyester imide, polyetheresteramide; Polyurethanes, in particular TPU or PUR type; Polysiloxanes; Celluloid, and mixtures or combinations thereof,
b) the reinforcing fibers are selected from the group consisting of glass fibers, carbon fibers and titanium whiskers, and in particular have a circular or plan cross section and / or a length of from 0.2 to 20 mm and / or a diameter of from 5 to 20 탆,
c) the weight ratio of reinforcing fibers in the thermoplastic molding compound is from 5 to 80% by weight, preferably from 20 to 70% by weight. 15. The method according to any one of claims 1 to 14,
a) The shear viscosity of the thermoplastic molding compounds measured according to ISO 11443 in the case of a shear rate of 100 to 10,000 Hz is preferably in the range of 10 to 10,000 Pas, particularly preferably in the range of 20 to 3,000 Pas, Is in the range of 30 to 1,000 Pas,
b) It may be adjusted / adjusted
c) the thermoplastic molding compound is injected into the injection mold cavity at a pressure of 50 to 2,000 bar. A molded part made of a thermoplastic molding compound made by a process according to any one of claims 1 to 15 and filled with reinforcing fibers, characterized in that the reinforcing fiber has at least one transition temperature Characterized in that it has an intrinsic anisotropic orientation of the reinforcing fibers during the manufacturing process along the locus of the channels which can be heated by the heating means. 17. The method of claim 16,
The orientation of the reinforcing fibers is defined by the following orientation tensor (a _ij ) of the n reinforcing fibers contained in one finite volume element,

The element a _ij is defined as follows,

The orientation of the fibers is determined by the diagonal elements a ₁₁ , a ₂₂ and a ₃₃ of the orientation tensor (a _ij )

or

Lt; RTI ID = 0.0 &gt; A vector of length 1 extending in parallel

Lt; / RTI &gt;

vector

Represents each considered finite volume element in the channel region that is heatable to one or more of the temperature changes in the local coordinate system,
The x-axis is fixed in each tangential direction to the trajectory of the channel which can be heated to one or more of the thermo-energies in each considered finite volume element,
The y-axis is oriented perpendicular to x,
The z-axis is oriented perpendicular to x and y,
The value of the element a ₁₁ of the orientation tensor (a _ij ) in each given finite volume element is 0.5 or more, preferably 0.5 to 0.98, more preferably 0.6 to 0.95, more preferably 0.65 to 0.9, especially 0.7 to 0.85 , An essentially anisotropic orientation is produced. An injection mold for producing a molded part made of a thermoplastic molding compound containing reinforcing fibers by injection molding,
At least one injection port for filling the cavity with a thermoplastic molding compound that is in a plasticized state and is comprised of reinforcing fibers, the at least one injection mold comprising: Is provided in one or more partial molds (gate positions)
Wherein one or more partial molds include channels that are heatable to one or more of the transition temperatures formed in a mold wall defining a partial mold or cavity. 19. The method of claim 18,
All of the partial molds have at least one breakthrough which generates a gap in the molded part from which the mold is manufactured,
A channel which is heatable by one or more of the temperature changes is formed in such a way that it completely or at least partly extends in a circumferential form with respect to the one or more breakthroughs and has a connection in the inflow direction and a connection in the outflow direction,
Characterized in that the connecting portion in the inflow direction and the connecting portion in the outflow direction are arranged offset from each other at the breakthrough protrusions and are preferably disposed offset from each other by 120 DEG or more and in particular on the opposite side of the brake- mold. 20. The method according to any one of claims 18 to 19,
The connecting portion in the inflow direction and the connecting portion in the outflow direction are respectively formed at the breakthrough protrusions by 60 degrees or less, preferably 50 degrees or less, more preferably 50 degrees or less from the main tensile load direction, Has a direction of less than 40 degrees, in particular less than 30 degrees. 21. The method according to any one of claims 18 to 20,
Wherein the injection mold has one or more overflow openings in fluid communication with the cavity such that when the injection mold is overfilled, the thermoplastic molding compound flows into the cavity, the overflow opening, and more preferably into the opening into the respective overflow cavity Wherein the injection mold comprises a plurality of injection molds. 22. The method according to any one of claims 18 to 21,
Characterized in that the channel which can be heated by one or more temperature changes starts at the gate position of the injection mold and preferably ends at one or more overflow openings. 23. The method according to any one of claims 18 to 22,
Characterized in that the connection in the inflow direction continues to the gate position of the injection mold and / or the connection in the outflow direction continues to the overflow opening. 24. The method according to any one of claims 18 and 23,
a) the sum of the channel areas heatable by one or more of the temperature changes is comprised between 1 and 50%, preferably between 3 and 30%, particularly preferably between 4 and 20%, in particular between 5 and 10% of the internal surface of the injection mold cavity / Configured
b) a channel which is heatable by one or more thermocouples is formed into a strip which is preferably heatable at a temperature which has a constant width, said width being preferably 0.2 to 30 mm, preferably 0.5 to 10 mm. .

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